1 files changed, 140 insertions, 93 deletions

diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 6788e73b6681..33eafb71e4f3 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -1,15 +1,18 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Landlock LSM - System call implementations and user space interfaces
+ * Landlock - System call implementations and user space interfaces
  *
  * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
  * Copyright © 2018-2020 ANSSI
+ * Copyright © 2021-2025 Microsoft Corporation
  */
 
 #include <asm/current.h>
 #include <linux/anon_inodes.h>
+#include <linux/bitops.h>
 #include <linux/build_bug.h>
 #include <linux/capability.h>
+#include <linux/cleanup.h>
 #include <linux/compiler_types.h>
 #include <linux/dcache.h>
 #include <linux/err.h>
@@ -27,6 +30,7 @@
 #include <uapi/linux/landlock.h>
 
 #include "cred.h"
+#include "domain.h"
 #include "fs.h"
 #include "limits.h"
 #include "net.h"
@@ -97,8 +101,9 @@ static void build_check_abi(void)
 	 */
 	ruleset_size = sizeof(ruleset_attr.handled_access_fs);
 	ruleset_size += sizeof(ruleset_attr.handled_access_net);
+	ruleset_size += sizeof(ruleset_attr.scoped);
 	BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size);
-	BUILD_BUG_ON(sizeof(ruleset_attr) != 16);
+	BUILD_BUG_ON(sizeof(ruleset_attr) != 24);
 
 	path_beneath_size = sizeof(path_beneath_attr.allowed_access);
 	path_beneath_size += sizeof(path_beneath_attr.parent_fd);
@@ -149,7 +154,14 @@ static const struct file_operations ruleset_fops = {
 	.write = fop_dummy_write,
 };
 
-#define LANDLOCK_ABI_VERSION 4
+/*
+ * The Landlock ABI version should be incremented for each new Landlock-related
+ * user space visible change (e.g. Landlock syscalls).  This version should
+ * only be incremented once per Linux release, and the date in
+ * Documentation/userspace-api/landlock.rst should be updated to reflect the
+ * UAPI change.
+ */
+const int landlock_abi_version = 7;
 
 /**
  * sys_landlock_create_ruleset - Create a new ruleset
@@ -158,21 +170,27 @@ static const struct file_operations ruleset_fops = {
  *        the new ruleset.
  * @size: Size of the pointed &struct landlock_ruleset_attr (needed for
  *        backward and forward compatibility).
- * @flags: Supported value: %LANDLOCK_CREATE_RULESET_VERSION.
+ * @flags: Supported values:
+ *
+ *         - %LANDLOCK_CREATE_RULESET_VERSION
+ *         - %LANDLOCK_CREATE_RULESET_ERRATA
  *
  * This system call enables to create a new Landlock ruleset, and returns the
  * related file descriptor on success.
  *
- * If @flags is %LANDLOCK_CREATE_RULESET_VERSION and @attr is NULL and @size is
- * 0, then the returned value is the highest supported Landlock ABI version
- * (starting at 1).
+ * If %LANDLOCK_CREATE_RULESET_VERSION or %LANDLOCK_CREATE_RULESET_ERRATA is
+ * set, then @attr must be NULL and @size must be 0.
  *
  * Possible returned errors are:
  *
  * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
- * - %EINVAL: unknown @flags, or unknown access, or too small @size;
- * - %E2BIG or %EFAULT: @attr or @size inconsistencies;
+ * - %EINVAL: unknown @flags, or unknown access, or unknown scope, or too small @size;
+ * - %E2BIG: @attr or @size inconsistencies;
+ * - %EFAULT: @attr or @size inconsistencies;
  * - %ENOMSG: empty &landlock_ruleset_attr.handled_access_fs.
+ *
+ * .. kernel-doc:: include/uapi/linux/landlock.h
+ *     :identifiers: landlock_create_ruleset_flags
  */
 SYSCALL_DEFINE3(landlock_create_ruleset,
 		const struct landlock_ruleset_attr __user *const, attr,
@@ -189,9 +207,15 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
 		return -EOPNOTSUPP;
 
 	if (flags) {
-		if ((flags == LANDLOCK_CREATE_RULESET_VERSION) && !attr &&
-		    !size)
-			return LANDLOCK_ABI_VERSION;
+		if (attr || size)
+			return -EINVAL;
+
+		if (flags == LANDLOCK_CREATE_RULESET_VERSION)
+			return landlock_abi_version;
+
+		if (flags == LANDLOCK_CREATE_RULESET_ERRATA)
+			return landlock_errata;
+
 		return -EINVAL;
 	}
 
@@ -213,9 +237,14 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
 	    LANDLOCK_MASK_ACCESS_NET)
 		return -EINVAL;
 
+	/* Checks IPC scoping content (and 32-bits cast). */
+	if ((ruleset_attr.scoped | LANDLOCK_MASK_SCOPE) != LANDLOCK_MASK_SCOPE)
+		return -EINVAL;
+
 	/* Checks arguments and transforms to kernel struct. */
 	ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs,
-					  ruleset_attr.handled_access_net);
+					  ruleset_attr.handled_access_net,
+					  ruleset_attr.scoped);
 	if (IS_ERR(ruleset))
 		return PTR_ERR(ruleset);
 
@@ -234,31 +263,21 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
 static struct landlock_ruleset *get_ruleset_from_fd(const int fd,
 						    const fmode_t mode)
 {
-	struct fd ruleset_f;
+	CLASS(fd, ruleset_f)(fd);
 	struct landlock_ruleset *ruleset;
 
-	ruleset_f = fdget(fd);
-	if (!ruleset_f.file)
+	if (fd_empty(ruleset_f))
 		return ERR_PTR(-EBADF);
 
 	/* Checks FD type and access right. */
-	if (ruleset_f.file->f_op != &ruleset_fops) {
-		ruleset = ERR_PTR(-EBADFD);
-		goto out_fdput;
-	}
-	if (!(ruleset_f.file->f_mode & mode)) {
-		ruleset = ERR_PTR(-EPERM);
-		goto out_fdput;
-	}
-	ruleset = ruleset_f.file->private_data;
-	if (WARN_ON_ONCE(ruleset->num_layers != 1)) {
-		ruleset = ERR_PTR(-EINVAL);
-		goto out_fdput;
-	}
+	if (fd_file(ruleset_f)->f_op != &ruleset_fops)
+		return ERR_PTR(-EBADFD);
+	if (!(fd_file(ruleset_f)->f_mode & mode))
+		return ERR_PTR(-EPERM);
+	ruleset = fd_file(ruleset_f)->private_data;
+	if (WARN_ON_ONCE(ruleset->num_layers != 1))
+		return ERR_PTR(-EINVAL);
 	landlock_get_ruleset(ruleset);
-
-out_fdput:
-	fdput(ruleset_f);
 	return ruleset;
 }
 
@@ -269,35 +288,28 @@ out_fdput:
  */
 static int get_path_from_fd(const s32 fd, struct path *const path)
 {
-	struct fd f;
-	int err = 0;
+	CLASS(fd_raw, f)(fd);
 
 	BUILD_BUG_ON(!__same_type(
 		fd, ((struct landlock_path_beneath_attr *)NULL)->parent_fd));
 
-	/* Handles O_PATH. */
-	f = fdget_raw(fd);
-	if (!f.file)
+	if (fd_empty(f))
 		return -EBADF;
 	/*
 	 * Forbids ruleset FDs, internal filesystems (e.g. nsfs), including
 	 * pseudo filesystems that will never be mountable (e.g. sockfs,
 	 * pipefs).
 	 */
-	if ((f.file->f_op == &ruleset_fops) ||
-	    (f.file->f_path.mnt->mnt_flags & MNT_INTERNAL) ||
-	    (f.file->f_path.dentry->d_sb->s_flags & SB_NOUSER) ||
-	    d_is_negative(f.file->f_path.dentry) ||
-	    IS_PRIVATE(d_backing_inode(f.file->f_path.dentry))) {
-		err = -EBADFD;
-		goto out_fdput;
-	}
-	*path = f.file->f_path;
+	if ((fd_file(f)->f_op == &ruleset_fops) ||
+	    (fd_file(f)->f_path.mnt->mnt_flags & MNT_INTERNAL) ||
+	    (fd_file(f)->f_path.dentry->d_sb->s_flags & SB_NOUSER) ||
+	    d_is_negative(fd_file(f)->f_path.dentry) ||
+	    IS_PRIVATE(d_backing_inode(fd_file(f)->f_path.dentry)))
+		return -EBADFD;
+
+	*path = fd_file(f)->f_path;
 	path_get(path);
-
-out_fdput:
-	fdput(f);
-	return err;
+	return 0;
 }
 
 static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
@@ -322,7 +334,7 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
 		return -ENOMSG;
 
 	/* Checks that allowed_access matches the @ruleset constraints. */
-	mask = landlock_get_raw_fs_access_mask(ruleset, 0);
+	mask = ruleset->access_masks[0].fs;
 	if ((path_beneath_attr.allowed_access | mask) != mask)
 		return -EINVAL;
 
@@ -378,8 +390,7 @@ static int add_rule_net_port(struct landlock_ruleset *ruleset,
  *		with the new rule.
  * @rule_type: Identify the structure type pointed to by @rule_attr:
  *             %LANDLOCK_RULE_PATH_BENEATH or %LANDLOCK_RULE_NET_PORT.
- * @rule_attr: Pointer to a rule (only of type &struct
- *             landlock_path_beneath_attr for now).
+ * @rule_attr: Pointer to a rule (matching the @rule_type).
  * @flags: Must be 0.
  *
  * This system call enables to define a new rule and add it to an existing
@@ -390,25 +401,26 @@ static int add_rule_net_port(struct landlock_ruleset *ruleset,
  * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
  * - %EAFNOSUPPORT: @rule_type is %LANDLOCK_RULE_NET_PORT but TCP/IP is not
  *   supported by the running kernel;
- * - %EINVAL: @flags is not 0, or inconsistent access in the rule (i.e.
+ * - %EINVAL: @flags is not 0;
+ * - %EINVAL: The rule accesses are inconsistent (i.e.
  *   &landlock_path_beneath_attr.allowed_access or
- *   &landlock_net_port_attr.allowed_access is not a subset of the
- *   ruleset handled accesses), or &landlock_net_port_attr.port is
- *   greater than 65535;
- * - %ENOMSG: Empty accesses (e.g. &landlock_path_beneath_attr.allowed_access);
+ *   &landlock_net_port_attr.allowed_access is not a subset of the ruleset
+ *   handled accesses)
+ * - %EINVAL: &landlock_net_port_attr.port is greater than 65535;
+ * - %ENOMSG: Empty accesses (e.g. &landlock_path_beneath_attr.allowed_access is
+ *   0);
  * - %EBADF: @ruleset_fd is not a file descriptor for the current thread, or a
  *   member of @rule_attr is not a file descriptor as expected;
  * - %EBADFD: @ruleset_fd is not a ruleset file descriptor, or a member of
  *   @rule_attr is not the expected file descriptor type;
  * - %EPERM: @ruleset_fd has no write access to the underlying ruleset;
- * - %EFAULT: @rule_attr inconsistency.
+ * - %EFAULT: @rule_attr was not a valid address.
  */
 SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
 		const enum landlock_rule_type, rule_type,
 		const void __user *const, rule_attr, const __u32, flags)
 {
-	struct landlock_ruleset *ruleset;
-	int err;
+	struct landlock_ruleset *ruleset __free(landlock_put_ruleset) = NULL;
 
 	if (!is_initialized())
 		return -EOPNOTSUPP;
@@ -424,17 +436,12 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
 
 	switch (rule_type) {
 	case LANDLOCK_RULE_PATH_BENEATH:
-		err = add_rule_path_beneath(ruleset, rule_attr);
-		break;
+		return add_rule_path_beneath(ruleset, rule_attr);
 	case LANDLOCK_RULE_NET_PORT:
-		err = add_rule_net_port(ruleset, rule_attr);
-		break;
+		return add_rule_net_port(ruleset, rule_attr);
 	default:
-		err = -EINVAL;
-		break;
+		return -EINVAL;
 	}
-	landlock_put_ruleset(ruleset);
-	return err;
 }
 
 /* Enforcement */
@@ -443,7 +450,11 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
  * sys_landlock_restrict_self - Enforce a ruleset on the calling thread
  *
  * @ruleset_fd: File descriptor tied to the ruleset to merge with the target.
- * @flags: Must be 0.
+ * @flags: Supported values:
+ *
+ *         - %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF
+ *         - %LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON
+ *         - %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
  *
  * This system call enables to enforce a Landlock ruleset on the current
  * thread.  Enforcing a ruleset requires that the task has %CAP_SYS_ADMIN in its
@@ -453,7 +464,7 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
  * Possible returned errors are:
  *
  * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
- * - %EINVAL: @flags is not 0.
+ * - %EINVAL: @flags contains an unknown bit.
  * - %EBADF: @ruleset_fd is not a file descriptor for the current thread;
  * - %EBADFD: @ruleset_fd is not a ruleset file descriptor;
  * - %EPERM: @ruleset_fd has no read access to the underlying ruleset, or the
@@ -461,14 +472,19 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
  *   %CAP_SYS_ADMIN in its namespace.
  * - %E2BIG: The maximum number of stacked rulesets is reached for the current
  *   thread.
+ *
+ * .. kernel-doc:: include/uapi/linux/landlock.h
+ *     :identifiers: landlock_restrict_self_flags
  */
 SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 		flags)
 {
-	struct landlock_ruleset *new_dom, *ruleset;
+	struct landlock_ruleset *new_dom,
+		*ruleset __free(landlock_put_ruleset) = NULL;
 	struct cred *new_cred;
 	struct landlock_cred_security *new_llcred;
-	int err;
+	bool __maybe_unused log_same_exec, log_new_exec, log_subdomains,
+		prev_log_subdomains;
 
 	if (!is_initialized())
 		return -EOPNOTSUPP;
@@ -481,44 +497,75 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 	    !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
 		return -EPERM;
 
-	/* No flag for now. */
-	if (flags)
+	if ((flags | LANDLOCK_MASK_RESTRICT_SELF) !=
+	    LANDLOCK_MASK_RESTRICT_SELF)
 		return -EINVAL;
 
-	/* Gets and checks the ruleset. */
-	ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_READ);
-	if (IS_ERR(ruleset))
-		return PTR_ERR(ruleset);
+	/* Translates "off" flag to boolean. */
+	log_same_exec = !(flags & LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF);
+	/* Translates "on" flag to boolean. */
+	log_new_exec = !!(flags & LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON);
+	/* Translates "off" flag to boolean. */
+	log_subdomains = !(flags & LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF);
+
+	/*
+	 * It is allowed to set LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF with
+	 * -1 as ruleset_fd, but no other flag must be set.
+	 */
+	if (!(ruleset_fd == -1 &&
+	      flags == LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF)) {
+		/* Gets and checks the ruleset. */
+		ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_READ);
+		if (IS_ERR(ruleset))
+			return PTR_ERR(ruleset);
+	}
 
 	/* Prepares new credentials. */
 	new_cred = prepare_creds();
-	if (!new_cred) {
-		err = -ENOMEM;
-		goto out_put_ruleset;
-	}
+	if (!new_cred)
+		return -ENOMEM;
+
 	new_llcred = landlock_cred(new_cred);
 
+#ifdef CONFIG_AUDIT
+	prev_log_subdomains = !new_llcred->log_subdomains_off;
+	new_llcred->log_subdomains_off = !prev_log_subdomains ||
+					 !log_subdomains;
+#endif /* CONFIG_AUDIT */
+
+	/*
+	 * The only case when a ruleset may not be set is if
+	 * LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF is set and ruleset_fd is -1.
+	 * We could optimize this case by not calling commit_creds() if this flag
+	 * was already set, but it is not worth the complexity.
+	 */
+	if (!ruleset)
+		return commit_creds(new_cred);
+
 	/*
 	 * There is no possible race condition while copying and manipulating
 	 * the current credentials because they are dedicated per thread.
 	 */
 	new_dom = landlock_merge_ruleset(new_llcred->domain, ruleset);
 	if (IS_ERR(new_dom)) {
-		err = PTR_ERR(new_dom);
-		goto out_put_creds;
+		abort_creds(new_cred);
+		return PTR_ERR(new_dom);
 	}
 
+#ifdef CONFIG_AUDIT
+	new_dom->hierarchy->log_same_exec = log_same_exec;
+	new_dom->hierarchy->log_new_exec = log_new_exec;
+	if ((!log_same_exec && !log_new_exec) || !prev_log_subdomains)
+		new_dom->hierarchy->log_status = LANDLOCK_LOG_DISABLED;
+#endif /* CONFIG_AUDIT */
+
 	/* Replaces the old (prepared) domain. */
 	landlock_put_ruleset(new_llcred->domain);
 	new_llcred->domain = new_dom;
 
-	landlock_put_ruleset(ruleset);
-	return commit_creds(new_cred);
-
-out_put_creds:
-	abort_creds(new_cred);
+#ifdef CONFIG_AUDIT
+	new_llcred->domain_exec |= BIT(new_dom->num_layers - 1);
+#endif /* CONFIG_AUDIT */
 
-out_put_ruleset:
-	landlock_put_ruleset(ruleset);
-	return err;
+	return commit_creds(new_cred);
 }